Decompression bomb in ezstd lets attackers exhaust BEAM memory
Key facts
- Attack vector
- Local
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- —
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA.
Summary
silviucpp ezstd from 1.0.5 before 1.2.5 is affected. The ezstd:decompress_using_ddict/2 function passes the content size declared in a zstd frame directly to memory allocation, skipping the 1 GiB size check that ezstd:decompress/1 applies (Improper Handling of Highly Compressed Data, CWE-409). A local attacker without privileges can supply a small crafted zstd frame that makes the Erlang VM exhaust memory and terminate, because the allocation happens inside a NIF.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
Description from the CNA
Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in silviucpp ezstd allows an attacker who supplies a zstd frame to ezstd:decompress_using_ddict/2 to exhaust memory and terminate the Erlang VM via a small frame that declares a very large content size. zstd_nif_decompress_using_ddict in c_src/ezstd_nif.cc reads the frame's declared content size with ZSTD_getFrameContentSize and passes it directly to enif_make_new_binary, without the 1 GiB MAX_BUFFER_SIZE check that ezstd:decompress/1 applies before allocating. A valid 65,550-byte frame of RLE blocks declaring 2 GiB is rejected by ezstd:decompress/1 but is fully allocated and decompressed by the dictionary path. The allocation happens inside a NIF, so when it exceeds the memory available to the VM the operating system kills the whole node rather than the calling process. This issue affects ezstd: from 1.0.5 before 1.2.5.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
Update ezstd to version 1.2.5, the fixed version.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
- Fix · CNA ezstd (silviucpp) Fixed in 1.2.5
Vendor assessments
Timeline
- 2026-11-05 Threatist record created from CVE-2026-119434
- 2026-11-05 CVSS score added · CISA ADP
- 2026-11-05 CISA SSVC decision points changed
- 2026-11-05 Priority changed: MEDIUM → LOW
- 2026-11-05 Alias added: GHSA-p9j8-93gx-5h3x
- 2026-11-06 Affected versions changed · Red Hat
- 2026-11-06 CVSS score added · Red Hat
References
Sources
- CVE-2026-119434 · CVE Program
- CVE-2026-119434 · NVD
- FIRST EPSS
- GHSA-p9j8-93gx-5h3x · GitHub Advisory Database · CC BY 4.0
- CVE-2026-119434 · Red Hat security data · CC BY 4.0
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